The Birth-Time of the World | Page 3

the answer. The measurements applied to the
little objects render the explanation beyond question. They turn out to
be a quite extraordinary record of radioactive energy; a record
accumulated since remote geological times, and assuring us, indirectly,
of the stability of the chemical elements in general since the beginning
of the world. This assurance is, without proof, often assumed in our
views on the geological history of the Globe.

Skating is a discourse, with a recent addition supporting the original
thesis. It is an illustration of a common experience--the explanation of
an unimportant action involving principles the most influential
considered as a part of Nature's resources.
The address on The Latent Image deals with a subject which had been
approached by various writers before the time of my essay; but, so far
as I know, an explanation
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based on the facts of photo-electricity had not been attempted. Students
of this subject will notice that the views expressed are similar to those
subsequently put forward by Lenard and Saeland in explanation of
phosphorescence. The whole matter is of more practical importance
than appears at first sight, for the photoelectric nature of the effects
involved in the radiative treatment of many cruel diseases seems to be
beyond doubt.
It was in connection with photo-electric science that I was led to take
an interest in the application of radioactivity in medicine. The lecture
on The Use of Radium in Medicine deals with this subject. Towards the
conclusion of this essay reference will be found to a practical outcome
of such studies which, by improving on the methods, and facilitating
the application, of radioactive treatment, has, in the hands of skilled
medical men, already resulted in the alleviation of suffering.
Leaving out much which might well appear in a prefatory notice, a
word should yet be added respecting the illustrations of scenery. They
are a small selection from a considerable number of photographs taken
during my summer wanderings in the Alps in company with Henry H.
Dixon. An exception is Plate X, which is by the late Dr. Edward
Stapleton. From what has been said above, it will be gathered that these
illustrations are fitly included among pages which owe so much to
Alpine inspiration. They illustrate the
xv

subjects dealt with, and, it is to be hoped, they will in some cases recall
to the reader scenes which have in past times influenced his thoughts in
the same manner; scenes which in their endless perspective seem to
reduce to their proper insignificance the lesser things of life.
My thanks are due to Mr. John Murray for kindly consenting to the
reissue of the essay on _The Birth-time of the World_ from the pages
of _Science Progress_; to Messrs. Constable & Co. for leave to reprint
Pleochroic Haloes from Bedrock, and also to make some extracts from
_Radioactivity and Geology_; and to the Council of the Royal Dublin
Society for permission to republish certain papers from the Proceedings
of the Society.
_Iveagh Geological Laboratory, Trinity College, Dublin._
July, 1915.
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THE BIRTH-TIME OF THE WORLD [1]
LONG ago Lucretius wrote: "For lack of power to solve the question
troubles the mind with doubts, whether there was ever a birth-time of
the world and whether likewise there is to be any end." "And if" (he
says in answer) "there was no birth-time of earth and heaven and they
have been from everlasting, why before the Theban war and the
destruction of Troy have not other poets as well sung other themes?
Whither have so many deeds of men so often passed away, why live
they nowhere embodied in lasting records of fame? The truth methinks
is that the sum has but a recent date, and the nature of the world is new
and has but lately had its commencement."[2]
Thus spake Lucretius nearly 2,000 years ago. Since then we have
attained another standpoint and found very different limitations. To
Lucretius the world commenced with man, and the answer he would
give to his questions was in accord with his philosophy: he would date
the birth-time of the world from the time when

[1] A lecture delivered before the Royal Dublin Society, February 6th,
1914. Science Progress, vol. ix., p. 37
[2] De Rerum Natura, translated by H. A. J. Munro (Cambridge, 1886).
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poets first sang upon the earth. Modern Science has along with the
theory that the Earth dated its beginning with the advent of man, swept
utterly away this beautiful imagining. We can, indeed, find no
beginning of the world. We trace back events and come to barriers
which close our vista--barriers which, for all we know, may for ever
close it. They stand like the gates of ivory and of horn; portals from
which only dreams proceed; and Science cannot as yet say of